全文获取类型
收费全文 | 1775篇 |
免费 | 0篇 |
专业分类
综合类 | 4篇 |
化学工业 | 9篇 |
机械仪表 | 2篇 |
建筑科学 | 1篇 |
能源动力 | 1篇 |
轻工业 | 4篇 |
石油天然气 | 1篇 |
无线电 | 4篇 |
一般工业技术 | 4篇 |
冶金工业 | 1742篇 |
自动化技术 | 3篇 |
出版年
2020年 | 1篇 |
2014年 | 4篇 |
2013年 | 2篇 |
2012年 | 2篇 |
2011年 | 2篇 |
2009年 | 1篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2004年 | 2篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2000年 | 1篇 |
1999年 | 58篇 |
1998年 | 616篇 |
1997年 | 306篇 |
1996年 | 177篇 |
1995年 | 98篇 |
1994年 | 82篇 |
1993年 | 111篇 |
1992年 | 16篇 |
1991年 | 18篇 |
1990年 | 25篇 |
1989年 | 29篇 |
1988年 | 19篇 |
1987年 | 14篇 |
1986年 | 26篇 |
1985年 | 9篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 16篇 |
1980年 | 13篇 |
1978年 | 5篇 |
1977年 | 32篇 |
1976年 | 75篇 |
1975年 | 1篇 |
排序方式: 共有1775条查询结果,搜索用时 31 毫秒
101.
JM LaLonde B Zhao CA Janson KJ D'Alessio MS McQueney MJ Orsini CM Debouck WW Smith 《Canadian Metallurgical Quarterly》1999,38(3):862-869
Cathepsin K is a cysteine protease present in human osteoclasts that plays an important role in bone resorption. Cathepsin K is synthesized as an inactive proenzyme and activated under conditions of low pH. Autoproteolytic processing of the N-terminal 99 amino acid propeptide produces the active, mature form of cathepsin K. It is presumed that the activation of procathepsin K in vivo occurs in the bone resorption pit, which has a low-pH environment. We have determined the structure of human procathepsin K at 2.8 A resolution. The structure of the mature enzyme domain within procathepsin K is virtually identical to that of mature cathepsin K. The fold of the propeptide of procathepsin K is similar to that observed in procathepsins B and L despite differences in length and sequence. A portion of the propeptide occupies the active site cleft of cathepsin K. Hydrophobic interactions, salt bridges, and hydrogen-bonding interactions are observed in the structure of the propeptide and between the propeptide and the mature enzyme of procathepsin K. These interactions suggest an explanation for the stability of the proenzyme. The structure of procathepsin K contributes to an understanding of the molecular basis of inhibition by the propeptide portion of the molecule and activation of this important member of the cysteine protease family. 相似文献
102.
Tinnitus is the perceived sensation of sound in the absence of acoustic stimulation. Individuals who suffer from it are commonly between the ages of 40 and 80 years. Tinnitus is often classified as objective or subjective, yet the pathophysiologic cause is still unknown. Subjective tinnitus is largely identified with hearing loss. Management of tinnitus is based on an individual approach; there is no single treatment or regimen for it. 相似文献
103.
104.
BI Reiner EL Siegel KJ French RS Dentry WT Mazan MJ Maroney 《Canadian Metallurgical Quarterly》1997,17(6):1487-1495
The authors demonstrate the use of radiography in the investigation of an historic painting and describe the potential benefits of computed radiography compared with conventional screen-film radiography. The subject for the comparison was a 16 x 19-foot oil-on-canvas painting, Scipio Africanus Freeing Massiva, by Giovanni Battista Tiepolo. Radiographs of the painting were obtained by using a portable, industrial radiographic unit and both conventional screen-film and photostimulable phosphor plate cassettes. For this investigation, computed radiography had a number of advantages over screen-film radiography, largely due to its wider dynamic range and its capabilities for enhancing the digital images with image processing tools such as magnification, edge enhancement, colorization, and airbrushing. The ability to electronically combine images from the large painting into a single composite image file was extremely valuable, as this technique was much less cumbersome and resulted in much higher quality composite images than could be achieved with conventional radiography. An additional advantage of computed radiography includes the capability to easily archive and transmit these images in a digital format for subsequent review. 相似文献
105.
UVB irradiation alters cellular responses to cytokines: role in extracellular matrix gene expression
VP Werth KJ Williams EA Fisher M Bashir J Rosenbloom X Shi 《Canadian Metallurgical Quarterly》1997,108(3):290-294
Chronic myeloid leukemia course was evaluated versus sex in 271 patients. Chronic stage involved more pronounced leukocytosis, thrombocytosis and splenomegaly in females, the latter showing higher susceptibility to anemia. As a result, treatment has to deal with a greater mass of tumor. A relatively longer survival time in males (44 and 42 months, respectively) suggest a higher effectiveness of therapy in such patients. When diagnosed, leukocytosis, thrombocytosis, enhanced splenomegaly and anemia should be regarded as factors of unfavorable prognosis. 相似文献
106.
PURPOSE: To evaluate fast spin-echo and multi-shot echo-planar fluid-attenuated inversion recovery (FLAIR) sequences in paediatric brain imaging. MATERIALS AND METHODS: Matched images from 32 patients with suspected tumour or white matter disease were independently evaluated by two paediatric neuroradiologists. The observer preferences for image quality and lesion detection were analysed for differences between fast spin-echo FLAIR and multi-shot echo-planar FLAIR. Diagnostic quality was compared with that of fast spin-echo T2-weighted images. RESULTS: Images of a diagnostic quality equivalent to that of fast spin-echo T2-weighted images were achieved with both FLAIR techniques. Grey and white matter differentiation and cerebrospinal fluid (CSF) nulling were significantly better on fast spin-echo FLAIR sequences. CSF flow artefact was reduced on multi-shot echo-planar FLAIR. There was no difference in lesion detection. Fast spin-echo FLAIR images were visually preferred at the expense of longer imaging time. CONCLUSION: Fast FLAIR techniques are complementary to fast spin-echo T2-weighted sequences in imaging of the paediatric brain. We find that the fast spin-echo FLAIR sequence is preferable to the multi-shot echo-planar technique. 相似文献
107.
108.
Body image, as measured by the Appearance Evaluation and Body Areas Satisfaction scales of the Multidimensional Body-Self Relations Questionnaire (T.F. Cash, 1994b), was assessed in 59 obese women before, during, and after 48 weeks of weight loss treatment. Before treatment, positive ratings of body image were associated with higher levels of self-esteem, lower levels of dysphoria, and fewer previous diets. After 24 weeks and a mean weight loss of 19.4 kg (SD = 6.5), participants showed significant (p < .0001) improvements in body image. A small weight gain from Week 24 to Week 48 was associated with a slight but significant worsening in both measures of body image. Nevertheless, after 48 weeks and a mean weight loss of 16.3 kg (SD = 7.1), body image was significantly improved from baseline (p < .0001). Changes in body image were not related to changes in weight. Future studies are needed to separate the effects of treatment and weight loss on body image in obese persons. 相似文献
109.
110.
KJ McDonagh 《Canadian Metallurgical Quarterly》1998,22(2):22-29
This author describes the advantages of having a nursing, academic, and experiential background for career progression in the health care world. The combination of nursing and business competencies provide for a well-prepared leader in a rapidly changing health care environment. An historical perspective on nurses as leaders in health care as well as competencies required for health care leaders for the future is described. 相似文献